In his 41 years on earth so far, Luis von Ahn has changed the world three times. People still blame him for the first.
That invention, which had its public debut on Yahoo in 2000, had a mouthful of a name; the Guatemalan-born computer scientist called it a “completely automated public Turing test to tell computers and humans apart,” or “Captcha” for short. Captchas, you’ll recall, are those often-agonizing boxes of stretched and twisted letters that mortals must correctly identify and retype to gain access to certain websites. That invention, says von Ahn, has on multiple occasions provoked strangers to tell him, “Oh, my God, I hate you.”
For all the fleeting angst they may have caused, though, Captchas have long been effective in preventing antisocial types from using computers—whose optical readers, until recently, had trouble reading such misshapen type—to rapidly buy up tickets on Ticketmaster, sign up for millions of email accounts, and do a host of other spammy and scammy things.
Captchas also unfortunately have consumed countless hours of exertion (albeit in 10-second intervals) as users strain to decipher the characters. So von Ahn, now a consulting professor at Carnegie Mellon and winner of a MacArthur “genius” grant, wondered, What better thing could people do with that same 10 seconds of effort? The answer was ReCaptcha—which ingeniously tweaked the Captcha test so that web surfers actually deciphered the hard-to-read text of ancient manuscripts as they proved they weren’t bots. With ReCaptcha, which Google bought in 2009, von Ahn crowdsourced the decoding of lost literature—by 35 million words a day.
Which brings us to invention No. 3. In 2011, von Ahn and one of his former graduate students at Carnegie Mellon, Severin Hacker, created Duolingo, No. 36 on Fortune’s 2019 Change the World list. Their language-learning app, whose free, ad-supported programs (and a paid option) are actively used by 28 million people, has once again mastered the art of converting human downtime into something valuable: the ability to speak a foreign tongue. In the process, they are helping save a few from extinction too. Among the 36 languages that Duolingo teaches, three—Hawaiian, Navajo, and Irish—were once in danger of fading into history. In Ireland, for instance, fewer than 75,000 people speak Irish, or Gaeilge, daily; today, 4.4 million budding linguists are learning to labhair on Duolingo. When new acquaintances learn that von Ahn built it, they tell him, “Oh, my God, I love you.”
Happily, von Ahn and his team can afford to keep being loved: Duolingo’s projected revenues for this year are $86 million—more than double 2018’s take of $36 million—and he expects sales to roughly double again next year. The growth, in turn, has allowed the serial inventor to invest in finding even better ways to help people learn languages—and to fund his next project: teaching people how to read.
Our fifth annual Change the World package—my favorite of Fortune’s many benchmark lists—offers a rich supply of companies that are finding sustainable (and often profitable) ways to address societal challenges. As always, we’re not weighing companies on a scale of “good” or “bad”—we couldn’t if we tried. Nor are we suggesting that the projects we’re highlighting absolve companies of things they may be doing that aren’t beneficial for society. (Read Adam Lashinsky’s probing interview with Anand Giridharadas for a more skeptical view.)
But we think doing well by doing good is a smart way to change the world. Let us know what you think, at [email protected]
A version of this article appears in the September 2019 issue of Fortune with the headline "Translating Success."
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